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Why isn't font rendered in HTML when surronded by "

I have some HTML stored in a database and I am generating an static HTML file out of it. However when i open the file in the browser, the font doesn't render as I expect it.
I have tracked down the problem and I see it is because of & quot;
<p><span style="font-family: "Roboto Regular";">Some text</span></p>
Now if I replace the & quot; with double quotes, it works fine.
This is also generated through C#. What is the best approach to fix this?
Should I just use Replace function to convert them to quotes or is there a library that I can use to do it more efficiently? or is it even simpler to fix.
Thanks for your thoughts.

You can use System.Web.HttpUtility.HtmlDecode (and Encode) to handle this sort of thing.
However you should be asking yourself why your font string includes HTML encoded characters.

HTML is spewed out as is and not parsed until it reaches the browser. This is a security measure to ensure that no malicious code can be run in the browser. I will recommend you use the Replace function you suggest. If you want to take security to the next level, I will suggest you encode the opening and closing braces of HTML tags and including that inside your Replace method.

I will explain why...
<p><span style="font-family: "Roboto Regular";">Some text</span></p>
Since you said c#, your code clearly shows that HtmlDecode doesn't decode quotes for font-family. This is caused by copy-paste html to database while using HtmlEncode as below.
HtmlEncode("<p><span style="font-family: "Roboto Regular";">Some text</span></p>");
As you notice above usage of quote in another quote is illegal in html unless it is escaped. That is why HtmlDecode thinks this is escaped quote and leaves it as it is.
SOLUTION: You can replace the font-family quotes with single quote before HtmlEncode but this would create SQL issue to address which is replacing single quote with double single quotes. Off course you need to reverse it after HtmlDecode. HtmlEncoding again or replacing with double quotes would not fix the issue since you are creating another illegal quotes in quotes. That is why you need to simply replace [&quote;] with single quote ['] and you can do this in frontend.
("<p><span style="font-family: "Roboto Regular";">Some text</span></p>").replace(""", "'");

C# URL QueryString Trouble

I have a WP7 project where I am using the below code. It normally works ok, but I am getting a strange result with some particular strings being passed through.
Service = "3q%23L3t41tGfXQDTaZMbn%23w%3D%3D?f"
NavigationService.Navigate(new Uri("/Details.xaml?service=" + Service, UriKind.Relative));
Next Page:
NavigationContext.QueryString.TryGetValue("service", out Service1);
Service1 now = 3q#L3t41tGfXQDTaZMbn#w==?f
Why has the string changed?

The string hasn't changed, but you're looking at it in two different ways.
The way to encode 3q#L3t41tGfXQDTaZMbn#w==?f for as URI content is as 3q%23L3t41tGfXQDTaZMbn%23w%3D%3D?f. (Actually, it's 3q%23L3t41tGfXQDTaZMbn%23w%3D%3D%3Ff but you get away with the ? near the end not being properly escaped to %3F in this context).
Your means of writing the string, expects to receive it escaped.
Your means of reading the string, returns it unescaped.
Things are working pretty much perfectly, really.
When you need to write the string again, then just escape it again:
Service = Uri.EscapeDataString(Service1);

In your first code snippet the string is URL Encoded.
In the 2nd code snippet, the string is URL Decoded.
They are essentially the same strings, just with encoding applied/removed.
For example: urlencoding # you get %23
For further reading check out this wikipedia article on encoding.
Since HttpUtility isn't part of WP7 Silverlight stack, I'd recommend using Uri.EscapeUriString to escape any URI's that have not been escaped.

You should probably URL encode the string if you want it to pass through unscathed.

How to use strange characters in a query string

I am using silverlight / ASP .NET and C#. What if I want to do this from silverlight for instance,
// I have left out the quotes to show you literally what the characters
// are that I want to use
string password = vtakyoj#"5
string encodedPassword = HttpUtility.UrlEncode(encryptedPassword, Encoding.UTF8);
// encoded password now = vtakyoj%23%225
URI uri = new URI("http://www.url.com/page.aspx#password=vtakyoj%23%225");
HttpPage.Window.Navigate(uri);
If I debug and look at the value of uri it shows up as this (we are still inside the silverlight app),
http://www.url.com?password=vtakyoj%23"5
So the %22 has become a quote for some reason.
If I then debug inside the page.aspx code (which of course is ASP .NET) the value of Request["password"] is actually this,
vtakyoj#"5
Which is the original value. How does that work? I would have thought that I would have to go,
HttpUtility.UrlDecode(Request["password"], Encoding.UTF8)
To get the original value.
Hope this makes sense?
Thanks.

First lets start with the UTF8 business. Esentially in this case there isn't any. When a string contains characters with in the standard ASCII character range (as your password does) a UTF8 encoding of that string is identical to a single byte ASCII string.
You start with this:-
vtakyoj#"5
The HttpUtility.UrlEncode somewhat aggressively encodes it to:-
vtakyoj%23%225
Its encoded the # and " however only # has special meaning in a URL. Hence when you view string value of the Uri object in Silverlight you see:-
vtakyoj%23"5
Edit (answering supplementary questions)
How does it know to decode it?
All data in a url must be properly encoded thats part of its being valid Url. Hence the webserver can rightly assume that all data in the query string has been appropriately encoded.
What if I had a real string which had %23 in it?
The correct encoding for "%23" would be "%3723" where %37 is %
Is that a documented feature of Request["Password"] that it decodes it?
Well I dunno, you'd have check the documentation I guess. BTW use Request.QueryString["Password"] the presence of this same indexer directly on Request was for the convenience of porting classic ASP to .NET. It doesn't make any real difference but its better for clarity since its easier to make the distinction between QueryString values and Form values.
if I don't use UFT8 the characters are being filtered out.
Aare you sure that non-ASCII characters may be present in the password? Can you provide an example you current example does not need encoding with UTF-8?

If Request["password"] is to work, you need "http://url.com?password=" + HttpUtility.UrlEncode("abc%$^##"). I.e. you need ? to separate the hostname.
Also the # syntax is username:password#hostname, but it has been disabled in IE7 and above IIRC.

Double/incomplete Parameter Url Encoding

In my web app, my parameters can contain all sorts of crazy characters (russian chars, slashes, spaces etc) and can therefor not always be represented as-is in a URL.
Sending them on their merry way will work in about 50% of the cases. Some things like spaces are already encoded somewhere (I'm guessing in the Html.BuildUrlFromExpression does). Other things though (like "/" and "*") are not.
Now I don't know what to do anymore because if I encode them myself, my encoding will get partially encoded again and end up wrong. If I don't encode them, some characters will not get through.
What I did is manually .replace() the characters I had problems with.
This is off course not a good idea.
Ideas?
--Edit--
I know there are a multitude of encoding/decoding libraries at my disposal.
It just looks like the mvc framework is already trying to do it for me, but not completely.
<a href="<%=Html.BuildUrlFromExpression<SearchController>(c=>c.Search("", 1, "a \v/&irdStr*ng"))%>" title="my hat's awesome!">
will render me
<a href="/Search.mvc/en/Search/1/a%20%5Cv/&irdStr*ng" title="my hat's awesome!">
Notice how the forward slash, asterisk and ampersand are not escaped.
Why are some escaped and others not? How can I now escape this properly?
Am I doing something wrong or is it the framework?

Parameters should be escaped using Uri.EscapeDataString:
string url = string.Format("http://www.foo.bar/page?name={0}&address={1}",
Uri.EscapeDataString("adlknad /?? lkm#"),
Uri.EscapeDataString(" qeio103 8182"));
Console.WriteLine(url);
Uri uri = new Uri(url);
string[] options = uri.Query.Split('?','&');
foreach (string option in options)
{
string[] parts = option.Split('=');
if (parts.Length == 2)
{
Console.WriteLine("{0} = {1}",parts[0],
Uri.UnescapeDataString(parts[1]));
}
}

AS others have mentioned, if you encode your string first you aviod the issue.
The MVC Framework is encoding characters that it knows it needs to encode, but leaving those that are valid URL characters (e.g. & % ? * /). This is because these are valid URL characters, although they are special chracters in a URL that might not acheive the result you are after.

Try using the Microsoft Anti-Cross Site Scripting library. It contains several Encode methods, which encode all the characters (including #, and characters in other languages). As for decoding, the browser should handle the encoded Url just fine, however if you need to manually decode the Url, use Uri.UnescapeDataString
Hope that helps.

Escaping of forward slahes and dots in path part of url is prohibited by security reason (althrough, it works in mono).

Html.BuildUrlFromExpression needs to be fixed then, would submit this upstream to the MVC project... alternatively do the encoding to the string before passing to BuildUrlFromExpression, and decode it when it comes back out on the other side.
It may not be readily fixable, as IIS may be handling the decoding of the url string beforehand... may need to do some more advanced encoding/decoding for alternative path characters in the utility methods, and decode on your behalf coming out.

I've seen similar posts on this. Too me, it looks like a flaw in MVC. The function would be more appropriately named "BuildUrlFromEncodedExpression". Whats worse, is that the called function needs to decode its input parameters. Yuk.
If there is any overlap between the characters encoded BuildUrlFromExpression() and the characters encoded by the caller (who, I think might fairly just encode any non-alphanumeric for simplicities sake) then you have potential for nasty bugs.

Server.URLEncode or HttpServerUtility.UrlEncode
I see what you're saying now - I didn't realize the question was specific to MVC. Looks like a limitation of that part of the MVC framework - particularly BuildUrlFromExpression is doing some URL encoding, but it knows that also needs some of those punctation as part of the framework URLs.
And also unfortunately, URLEncoding doesn't produce an invariant, i.e.
URLEncode(x) != URLEncode(URLEncode(x))
Wouldn't that be nice. Then you could pre-encode your variables and they wouldn't be double encoded.
There's probably an ASP.NET MVC framework best practice for this. I guess another thing you could do is encode into base64 or something that is URLEncode-invariant.

Have you tried using the Server.UrlEncode() method to do the encoding, and the Server.UrlDecode() method to decode?
I have not had any issues with using it for passing items.

QueryString malformed after URLDecode

I'm trying to pass in a Base64 string into a C#.Net web application via the QueryString. When the string arrives the "+" (plus) sign is being replaced by a space. It appears that the automatic URLDecode process is doing this. I have no control over what is being passed via the QueryString. Is there any way to handle this server side?
Example:
http://localhost:3399/Base64.aspx?VLTrap=VkxUcmFwIHNldCB0byAiRkRTQT8+PE0iIHBsdXMgb3IgbWludXMgNSBwZXJjZW50Lg==
Produces:
VkxUcmFwIHNldCB0byAiRkRTQT8 PE0iIHBsdXMgb3IgbWludXMgNSBwZXJjZW50Lg==
People have suggested URLEncoding the querystring:
System.Web.HttpUtility.UrlEncode(yourString)
I can't do that as I have no control over the calling routine (which is working fine with other languages).
There was also the suggestion of replacing spaces with a plus sign:
Request.QueryString["VLTrap"].Replace(" ", "+");
I had though of this but my concern with it, and I should have mentioned this to start, is that I don't know what other characters might be malformed in addition to the plus sign.
My main goal is to intercept the QueryString before it is run through the decoder.
To this end I tried looking at Request.QueryString.toString() but this contained the same malformed information. Is there any way to look at the raw QueryString before it is URLDecoded?
After further testing it appears that .Net expects everything coming in from the QuerString to be URL encoded but the browser does not automatically URL encode GET requests.

The suggested solution:
Request.QueryString["VLTrap"].Replace(" ", "+");
Should work just fine. As for your concern:
I had though of this but my concern with it, and I should have mentioned this to start, is that I don't know what other characters might be malformed in addition to the plus sign.
This is easy to alleviate by reading about base64. The only non alphanumeric characters that are legal in modern base64 are "/", "+" and "=" (which is only used for padding).
Of those, "+" is the only one that has special meaning as an escaped representation in URLs. While the other two have special meaning in URLs (path delimiter and query string separator), they shouldn't pose a problem.
So I think you should be OK.

You could manually replace the value (argument.Replace(' ', '+')) or consult the HttpRequest.ServerVariables["QUERY_STRING"] (even better the HttpRequest.Url.Query) and parse it yourself.
You should however try to solve the problem where the URL is given; a plus sign needs to get encoded as "%2B" in the URL because a plus otherwise represents a space.
If you don't control the inbound URLs, the first option would be preferred as you avoid the most errors this way.

I'm having this exact same issue except I have control over my URL. Even with Server.URLDecode and Server.URLEncode it doesn't convert it back to a + sign, even though my query string looks as follows:
http://localhost/childapp/default.aspx?TokenID=0XU%2fKUTLau%2bnSWR7%2b5Z7DbZrhKZMyeqStyTPonw1OdI%3d
When I perform the following.
string tokenID = Server.UrlDecode(Request.QueryString["TokenID"]);
it still does not convert the %2b back into a + sign. Instead I have to do the following:
string tokenID = Server.UrlDecode(Request.QueryString["TokenID"]);
tokenID = tokenID.Replace(" ", "+");
Then it works correctly. Really odd.

I had similar problem with a parameter that contains Base64 value and when it comes with '+'.
Only Request.QueryString["VLTrap"].Replace(" ", "+"); worked fine for me;
no UrlEncode or other encoding helping because even if you show encoded link on page yourself with '+' encoded as a '%2b' then it's browser that changes it to '+' at first when it showen and when you click it then browser changes it to empty space. So no way to control it as original poster says even if you show links yourself. The same thing with such links even in html emails.

If you use System.Uri.UnescapeDataString(yourString) it will ignore the +. This method should only be used in cases like yours where when the string was encoded using some sort of legacy approach either on the client or server.
See this blog post:
http://blogs.msdn.com/b/yangxind/archive/2006/11/09/don-t-use-net-system-uri-unescapedatastring-in-url-decoding.aspx

If you URLEncode the string before adding it to the URL you will not have any of those problems (the automatic URLDecode will return it to the original state).

Well, obviously you should have the Base64 string URLEncoded before sending it to the server.
If you cannot accomplish that, I would suggest simply replacing any embedded spaces back to +; since b64 strings are not suposed to have spaces, its a legitimate tactic...

System.Web.HttpUtility.UrlEncode(yourString) will do the trick.

As a quick hack you could replace space with plus character before base64-decoding.

I am by no means a C# developer but it looks like you need to url ENCODE your Base64 string before sending it as a url.

Can't you just assume a space is a + and replace it?
Request.QueryString["VLTrap"].Replace(" ", "+");
;)